The valuable part of a tree is the butt area where the felling cut is made and there has been increasing concern over the damage being done to this area by shear severing devices with the consequence of numerous proposals having been made adapting chain saws and circular center spindle mounted saw blades and cutting discs on felling heads for cutting trees. Chain saws, however, are fragile and thus subject to frequent failure. Circular saws, while they are more robust, are also more bulky. Also, they usually are run at higher speeds with an attendant increase in safety and saw damage hazards. Because of these drawbacks, applicant has adapted the rim driven saw principle. These saws are inherently compact as they do not need a central arbour for driving purposes. They can be robust in construction and operated at moderate to low speeds and thus avoid many of the disadvantages as well as safety and damage hazards associated with high speed, previously used circular saws.
One form of rim driven saw for applicant's intended purpose is disclosed in the aforementioned appplication Ser. No. 605,219.
Other rim driven type saws are also known, as for exapmle those disclosed in the following patents:
Canadian Patent No. 983,825 issued, Feb. 17, 1976--Jonsson PA1 Canadian Patent No. 994,647, issued Aug. 10, 1976--Wiklund PA1 U.S. Pat. No. 2,490,255, issued Dec. 6, 1949--Chase PA1 U.S. Pat. No. 2,599,495, issued June 3, 1952--Smith PA1 U.S. Pat. No. 2,701,590, issued Feb. 8, 1955--Barker PA1 U.S. Pat. No. 2,804,105, issued Aug. 27, 1957--Stone PA1 U.S. Pat. No. 2,972,363, issued Feb. 21, 1961--Santilli PA1 U.S. Pat. No. 3,930,310, issued, Jan. 6, 1976--Santilli PA1 U.S. Pat. No. 460,679, issued Oct. 6, 1891--Hammond
In addition to the foregoing there is commercially available a tree feller incorporating a rim driven saw distributed in Canada by Risley Equipment Ltd. of Grande Prairie, Alberta and is sold under the trade name "RotoSaw".
Applicant's device, as will be found hereinafter, incorporates a number of features and combinations thereof which distinguishes over the foregoing known devices.